Technical Reference Guide

4.8.3 I/O CONTROLLER FUNCTIONS

The I/O controller (used in desktop and minitower systems) contains various functions such as the keyboard/mouse interfaces, diskette interface, serial interfaces, and parallel interface. While the control of these interfaces uses standard AT-type I/O addressing (as described in chapter 5) the configuration of these functions occurs through indexed ports using PnP protocol. In these systems, hardware strapping selects I/O addresses 02Eh/02Fh at reset as the Index/Data ports for accessing the logical devices within the I/O contoller. Table 4-16 lists the PnP control registers for the LPC47B357.

Table 4-16LPC47B357 Control Registers

Table 4-16.

I/O Controller Control Registers

Index

Function

Reset Value

02h

Configuration Control

00h

03h

Reserved

 

07h

Logical Device (Interface) Select:

00h

 

00h

= Diskette Drive I/F

 

 

01h

= Rsvd

 

 

02h

= Rsvd

 

 

03h

= Parallel I/F

 

 

04h

= Serial I/F (UART 1)

 

 

05h

= Serial I/F (UART 2)

 

 

06h

= Rsvd

 

 

07h

= Keyboard I/F

 

 

08h

= Rsvd

 

 

09h

= Rsvd

 

 

0Ah = Runtime Reg. (GPIO Config.)

 

 

0Bh = Rsvd

 

20h

Super I/O ID Register (SID)

56H

21h

Revision

--

22h

Logical Device Power Control

00h

23h

Logical Device Power Management

00h

24h

PLL / Oscillator Control

04h

25-2Fh

Device specific [2]

--

NOTES:

Refer to LPC47B357 data sheet for detailed register information.

The configuration registers are accessed through I/O registers 2Eh (index) and 2Fh (data) after the configuration phase has been activated by writing 55h once to I/O port 2Eh. The BIOS then initiates each logical device and then deactivates the configuration phase by writing AAh to 2Eh.

Compaq Deskpro EXS and Workstation 300 Personal Computers 4-37

Featuring the Intel Pentium 4 Processor

First Edition - December 2000

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Compaq 850 manual 3 I/O Controller Functions, Controller Control Registers, Index Function Reset Value